Watching the water supply:

Southwest Washington bearing brunt of dry conditions

Although we don't expect much rain this time of year, one area of the state stands out for being drier than usual: Southwest Washington and most of the Olympic Peninsula.

The July 19, 2018, U.S. Drought Monitor map classifies

southwest Washington as having moderate drought-like

conditions. Much of the rest of the state is considered

abnormally dry.

The U.S. Drought Monitor map, one of the tools we use to assess state water supply conditions, classifies much of the region as experiencing moderate drought-like conditions. The map is updated weekly and available on our statewide water supply conditions webpage.

Streamflow data also point to low flows in the region.

We’re seeing many rivers and streams in southwest Washington run at record low levels. The Chehalis River near Grand Mound is running at 113 cubic feet per second—a flow level in the 1st percentile, meaning flows are so low they are exceeded 99 percent of the time for this time of year historically. The Willapa River near Willapa is at 20 cubic feet per second, which is in the 1.5 percentile, meaning the flow is exceeded 98.5 percent of the time for this time of year historically. Irrigators, fish and aquatic habitat are most affected by these low flows.

Citing low flows in the Cowlitz River, the city of Kelso has asked its residents to take  

The Chehalis River winds its way west of Chehalis (July 19, 2018). We're
seeing record low flows on parts of the river. 

voluntarily water conservation measures until water levels in the municipality’s water source improve. To the north, the city of Forks and two small Jefferson County water systems are also asking their customers to follow voluntary conservation measures.

NOAA’s climate prediction center is predicting warm, dry conditions for the rest of summer. We are closely monitoring water supply conditions and working with other state agencies to track impacts. If you’d like more detail, read our water supply webpage.

Are we in a drought emergency?

Under Washington State law, emergency drought conditions are identified when water supply in an area has or is predicted to have 75 percent of normal water supplies AND undue hardships expected as a result. 

Drought emergencies are declared using a formal process based on statute. At this time, we have not declared a drought emergency anywhere in the state.

A rain-fed water system

The hydrogeology of southwest Washington is unique. Water supplies rely heavily on rain and less on snowpack from the Cascade and Olympic mountains. This means the region’s water supplies are more sensitive to above-average temperatures and below-average precipitation like we’ve been experiencing.

The effects of the unseasonably warm and dry weather in May led us to issue water use curtailment notices. We asked 88 junior water right holders—mostly irrigators—in the Chehalis River basin to stop using river water until flows increase.  This is the fourth consecutive year we have issued curtailment orders or notices for junior surface water irrigation uses in the basin. It was also among the earliest dates we have curtailed this group of water users.

Office of Chehalis Basin

In 2016, the Legislature created the Office of Chehalis Basin within Ecology. While a main focus of the new office is to pursue long-term flood-damage reduction and restore aquatic habitat in the state’s second-largest river drainage system, the Office of Chehalis Basin is also tracking the impacts of the dry conditions.

By Kristin Johnson-Waggoner, communications manager

Curtailments come to the Chehalis River basin

Notice applies to outdoor water use only—mostly irrigation

The curtailment notice affects junior water right holders.

After an unseasonably warm and dry May, we have notified 93 junior water right holders in the Chehalis River basin that their access to surface water for irrigation is curtailed until streamflows increase in the state’s second largest watershed and drainage basin.

The water users have rights that are junior to (younger than) the 1976 instream flows set by state rule for the basin. Those junior water right holders need to stop diverting water from the Chehalis, Newaukum, Satsop, and Wynoochee rivers when flows are not being met to keep the water in the stream. We sent notification letters to the 93 junior water right holders on May 31.

This is the fourth consecutive year we have issued curtailment orders or notices for junior surface water irrigation uses in the Chehalis basin to comply with the regulation requirements. The curtailment notice does not apply to indoor water use or water for livestock.

As we’ve done in prior years, our staff will periodically visit the basin and are available to answer questions in person, by telephone, or email.

Check our website to see if instream flows are being met:

·        Lower Chehalis watershed

·        Upper Chehalis watershed

Unusual May weather

The Chehalis basin receives most of its runoff from rain, with some minor contributions from snowpack at higher elevations in headwater streams in the southern Olympic Mountains. Streamflows in the basin are lower than normal for this time of year. It’s been warm and dry in the Chehalis River basin and there is little melting snow left to compensate for the tightening water supply.

Instream flows protect rivers

The Newaukum River

We are required by law to protect senior water right users and adopted streamflows for rivers and streams to make sure there is enough water to meet the needs of people, farms, and fish. One of the most effective tools for protecting streamflows is to set instream flows, which are flow levels adopted into rule.

An instream flow rule was established in 1976 for Chehalis basin streams. Since then, newer water rights have been issued that are junior to the flow rule. When flows drop below the adopted levels, junior water rights (those established after the instream flow rule was adopted into law) can be temporarily interrupted in an effort to keep the protected amount of water in the stream. This means junior water rights are curtailed from withdrawing water until streamflows rise above the established flow levels.

Setting instream flows protects our streams, rivers, and lakes from new withdrawals that would harm instream resources including fish, wildlife, recreation, aesthetics, water quality, and navigation.

Read more about protecting streamflows. 

By Kristin Johnson-Waggoner, Water Resources Program